Gas turbine engines generally include an exhaust diffuser positioned downstream of the last stage of a turbine. Generally described, the exhaust diffuser converts the kinetic energy of the hot combustion gases exiting the last stage of the turbine into potential energy in the form of increased static pressure. The exhaust diffuser directs the hot combustion gases through a casing of increasing cross-sectional area in the direction of the flow. The exhaust diffuser generally includes a number of struts mounted onto a hub and enclosed by the casing.
The first section of the exhaust diffuser may account for a majority of the pressure recovery at all load points. The struts in this section, however, may create turbulence and flow losses, particularly if the struts or the bucket platform is flared forward. Hub strong inlet flow profiles also may contribute to the flow losses in that such profiles may concentrate a large amount of the hot combustion gas flow near the hub flow path with separation from the casing.